Drew Peterson once grabbed his wife around her neck and asked, "Why don't you just die?" according to a friend of Kathleen Savio's who testified in Peterson's murder trial today.

Peterson, 58, is on trial for killing Savio, his third wife, and making it look like an accident. She was found dead in her bathtub in 2004 and the death was initially ruled an accidental drowning. After Peterson's fourth wife, Stacy Peterson, vanished from their home in 2007, police exhumed Savio's body and reexamined it for signs of murder, finally charging Peterson.

"Kathy told me that her husband, Drew Peterson, said he could kill her, make her disappear," Parks said on the stand, according to ABC News affiliate WLS. Parks teared up as she recalled the conversation about Peterson grabbing Savio's neck.

"She unzipped the top, it opened and I saw marks on her neck," Parks said.

According to her testimony, Parks took nursing classes with Savio, but did not see her again after their graduation in December 2003. Savio died in February 2004.

When Parks heard of the death, she called the Will County State's Attorney's Office and asked if the case were being investigated, she testified today.

The testimony today marked the second day hearsay statements were allowed into the court transcript, following a significant decision Wednesday by Judge Edward Burmila to allow Savio's friends to testify about Peterson's alleged threats.

Kristen Anderson, who lived in Savio's basement after Savio and Peterson split up, said that Savio slept with a knife under her mattress because she was so afraid of Peterson.

"She showed me a knife that she kept in between her mattresses for protection," Anderson said.

Anderson recalled a conversation in which Savio confessed that Peterson once told her, "I could kill you and make it look like an accident."

After the statement, Anderson broke down in tears and had to leave the courtroom, according to WLS. She returned later and continued testifying about Peterson's threatening behavior, including an incident in which Peterson broke into the home, dressed in SWAT gear, and held a knife to Savio's throat while threatening her.

Anderson said she called police three times about Savio's case in 2004, but those calls were never returned.

Burmila's decision to allow the testimony was hailed by the prosecution, which has no physical evidence tying Peterson to the scene of the crime.